Icfft
Complex discrete inverse Fourier transform.
 
Loading        LOADSUB ALL FROM "FFT.HTS"
or LOADSUB FROM "MATHLIB.HTS"
or LOADSUB Icfft FROM "MATHLIB.HTS"
 
Usage                INTEGER Logn
COMPLEX A(*),F(*)
CALL Icfft(Logn,F(*),A(*))
 
Description                
Icfft calculates the discrete inverse Fourier transform of the sequence in the array F and stores the result in the array A. Logn is the base-2 log of the number of points in the sequences. The arrays A and F must contain at least 2Logn elements; if they have more than this number of elements, the extra elements are ignored and unmodified. The number of elements denoted by each permitted value of Logn is shown in the table below:
 
Logn                No. Elements (2Logn)
2                4
3                8
4                16
5                32
6                64
7                128
8                256
9                512
10                1024
11                2048
12                4096
13                8192
14                16384
 
 
The meaning of the values input to Icfft is the same as that for the values output by the Cfft routine; see the entry for the Cfft routine for a detailed explanation of the meaning of the values input to Icfft.
 
 
Errors                
Icfft causes an HTBasic error if its arguments are not of the types shown in the USAGE section, above, if Logn is not between 2 and 15, inclusive, or if the size of A or C is smaller than 2Logn.
 
See Also
Cfft, Ifft